The Army Reserve amount will be about $9000 per year. I realize the kids education will be expensive, but it looks like I can make as much or more in retirement as I do working. And yes,... the 70K spending is with two car payments, mortgage, and with 4 school aged kids living with us. There should come a day when the mortgage and kids cost will be gone (I hope).
Sorry for the slow response.
I can do a back-of-the-envelope calc to get a gut feel on FireCalc. The 55/56 looks plausible, it's all about the cushion.
I'd start the math by assuming you'll retire today. You've got $970k in current savings. Assign $30k to pay off the mortgage, and $216k to provide a bridge until Army Reserve pension and SS start. (I'm figuring the $216k provides 7 years at $26k followed by 2 years at $17k.) Adding $26k to your current $15k pension gives you a base income of $41k for each year in the future, leaving $29k to be funded by withdrawals from savings.
So you'd have $970k - $30k - $216k = $724k to provide annual income at some periodic withdrawal rate. Using 4% gives $29k which exactly hits the $70k target.
But, the $70k target includes mortgage, and the method above set aside enough to pay off the mortgage, so there's a cushion equal to the mortgage payments.
Most people here think that it's too risky to retire if you really
need 4% inflation adjusted in every year of retirement because the market has been known to go down sharply. If you've got FireCalc all set up, it me be good to look at the detail results (click the first box in the "Investigate" tab, then find the Excel link on the "Results" tab) to see the year-by-year portfolio balances and imagine living through the poorer years.
When I do the same math for retirement at 56, assuming your assets grow at 3% real, I see that 4% gives $35k withdrawals to add to the $41k base. That provides some cushion.
I think your biggest spending unkown is the kids. Suppose your current $70k includes $7.5k per year per child that goes away as each one leaves home. So you and your spouse are currently living on $40k per year (including house). That would mean pensions/SS will cover the two of you long term and you could (very theoretically) spend most of your savings on the children. That would give you a lot of room, but it assumes you two can really be comfortable living on just $40k. At any rate, I think I'd want to get a handle on what spending will go down when the kids leave home and talk to my spouse about how much we plan to spend on education and whatever else (weddings?) as the children move on. Those thoughts might swing your plans significantly one way or the other.